1. Field of the Invention
The present invention generally relates to a bi-level positive airway pressure support system, and, more particularly, to a bi-level positive pressure support system and method of providing bi-level positive pressure support in which the rise time of the transition of pressure from the expiratory phase of pressure support to the inspiratory phase is automatically adjusted.
2. Description of the Related Art
Pressure support systems that provide a flow of breathing gas to an airway of a patient at an elevated pressure to treat a medical disorder are well known. One basic form of pressure support system is a continuous positive airway pressure (CPAP) system, which typically involves providing a flow of breathing gas, such as air, to a patient's airway at a constant pressure throughout a patient's breathing cycle. When used to treat obstructive sleep apnea (OSA), for example, this constant pressure is provided at a level sufficient to overcome a patient's airway resistances.
It is also known to provide a bi-level positive pressure therapy in which the pressure of gas delivered to the patient varies with the patient's breathing cycle. In a bi-level pressure support system, an inspiratory positive airway pressure (IPAP) is provided during a patient's inspiratory phase of the breathing cycle and an expiratory positive airway pressure (EPAP) is provided during the expiratory phase. The EPAP is lower than the IPAP so that the patient exhales against a relatively low pressure as compared to the IPAP pressure, thereby increasing the comfort to the patient. The BiPAP® family of pressure support devices manufactured by Philips Respironics, Inc. of Murrysville, Pa., are examples of pressure support device that provide this bi-level form of pressure support therapy. In addition, several U.S. patents describe this bi-level pressure support system in detail, including U.S. Pat. Nos. 5,433,193; 5,313,937; 5,239,995; 5,148,802; 6,532,960; and 6,640,806, the contents of all of which are hereby expressly incorporated herein by reference as if set forth in their entirety herein.
Bi-level pressure support systems as just described are often used in home settings to treat various breathing disorders, such as, without limitation, OSA. Home use of a bi-level pressure support systems currently requires a skilled provider to visit the home of the patient at least one and often several times to make sure that the system is properly set-up to provide the appropriate type of therapy to the patient. Thus, setting up and maintaining bi-level pressure support systems for home use is currently a time consuming and therefore expensive proposition. Accordingly, features that would reduce this set up time and/or minimize follow-up visits to the patient's home are valued by healthcare providers.